(a) Field of the Invention
The present invention relates to a method and system for controlling a motor of an environmentally-friendly vehicle, and more particularly, to a method and system for controlling a motor of an environmentally-friendly vehicle that improves a vibration characteristic of a motor using a nonlinear model of the motor.
(b) Description of the Related Art
As is well known in the art, an environmentally-friendly vehicle generally includes a fuel cell vehicle, an electric vehicle, a plug-in electric vehicle, and a hybrid vehicle, and typically includes a motor (e.g., driving motor) to generate driving force. A hybrid vehicle, which is an example of the environmentally-friendly vehicle, uses an internal combustion engine and power of a battery together. In other words, the hybrid vehicle efficiently combines and uses power of the internal combustion engine and power of the motor.
The hybrid vehicle typically includes, for example, as illustrated in FIG. 9, an engine 10, a motor 20, an engine clutch 30 to adjust power between the engine 10 and the motor 20, a transmission 40, a differential gear apparatus 50, a battery 60, an integrated starter-generator 70 that starts the engine 10 or generates electricity by output of the engine 10, and wheels 80. Further, the hybrid vehicle may include a hybrid control unit (HCU) 200 configured to operate the hybrid vehicle, an engine control unit (ECU) 110 configured to operate the engine 10, a motor control unit (MCU) 120 configured to operate the motor 20; a transmission control unit (TCU) 140 configured to operate the transmission 40; and a battery control unit (BCU) 160 configured to operate and manage the battery 60.
The battery control unit 160 may be a battery management system (BMS). The integrated starter-generator 70 may be an integrated starter & generator (ISG), or a hybrid starter & generator (HSG). The hybrid vehicle may be driven in a driving mode, such as an electric vehicle (EV) mode, which is an electric vehicle mode using only power of the motor 20, a hybrid vehicle (HEV) mode, which uses rotational force of the engine 10 as main power, and uses rotational force of the motor 20 as auxiliary power, and a regenerative braking (RB) mode that collects braking and inertial energy during driving by braking or inertia of the vehicle through electric generation of the motor 20 to charge the battery 60.
The environmentally-friendly vehicle including the hybrid vehicle generally drives and controls the motor M via a controller 300 illustrated in FIG. 1. Referring to FIG. 1, the controller 300 that operates the motor M, which rotates at an electrical angular velocity (We) is configured to receive a torque command Te* from an external system, and perform a series of processes to obtain a torque output Te based on the torque command Te*. The torque command received in the controller 300 is transmitted to a current command generator 311 to generate a specific current command based on an operation condition of the motor M.
The current command generated in the current command generator 311 is transmitted to the voltage command generator 312. The current command transmitted to the voltage command generator 312 is converted to a voltage command to be applied to the motor M based on the operation condition of the motor M. The voltage command output from the voltage command generator 312 is transmitted to a pulse width modulation (PWM) command generator 313. The voltage command transmitted to the PWM command generator 313 is converted to a PWM command based on the operation condition of the motor M. The PWM command output from the PWM command generator 313 is transmitted to the PWM voltage generator 314. The PWM command transmitted to the PWM voltage generator 314 is converted to a voltage in a PWM form based on the operation condition of the motor M, and the converted PWM voltage is applied to the motor M to drive the motor M.
Moreover, in a system for controlling a motor of the environmentally-friendly vehicle, a current command controller (not illustrated) operated in a synchronous coordinate system selects Idsr* (d-axis stator Reference current) and Iqsr* (q-axis stator Reference current) as current commands based on the demanded torque Te*. The selected current commands Idsr* and Iqsr* are a combination of current commands that output the demanded torque Te*. The current command controller operated in the synchronous coordinate system operates the motor M to output the torque Te based on the demanded torque Te* through a series of processes to cause currents Idsr and Iqsr based on the current commands Idsr* and Iqsr* selected by the operation condition of the motor M to flow in the motor M.
However, when the currents Idsr and Iqsr based on the current commands Idsr* and Iqsr* flow in the motor M, a torque Te having a different aspect from that of the demanded torque Te* may be generated by an inherent characteristic of the motor M and the controller 300. Particularly, when the characteristic is repeated according to a rotation of a rotor of the motor M, torque output vibrates, and vibration of a vehicle may be caused for an environmentally-friendly vehicle in which a motor system including the motor and the controller generates principal driving force of the vehicle. Accordingly, in the controller controlling output of the motor in the environmentally-friendly vehicle, torque output based on states of the motor and the controller and a change in the state needs to be substantially uniform using a control method in which torque output is not changed based on characteristics of the motor and the controller.
The above information disclosed in this section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.